MOSCOW, AUG. 4 -- The Soviet Union and Iran agreed on new "large-scale" projects of economic cooperation and jointly criticized the U.S. naval presence in the Persian Gulf during a visit to Tehran by Soviet First Deputy Foreign Minister Yuli Vorontsov, the Tass news agency said today.

Vorontsov, conducting his second visit to Iran since June, held talks with President Ali Khamenei, Prime Minister Hussein Moussavi and Foreign Affairs Minister Ali Akbar Velayati during a three-day visit ending today, Tass said. Vorontsov is also due to visit Iraq during his tour.

The two sides expressed "mutual concern" over "the unprecedented build-up of U.S. military presence in the area," Tass said. It said Iran had supported Moscow's proposal for the withdrawal of all foreign naval ships from the Persian Gulf and for Iran and Iraq to refrain from actions that pose a threat to international shipping.

Western diplomats here said Vorontsov's visit was a sign of a modest improvement in ties between the Soviet Union and Iran as Moscow sought to take advantage of Tehran's rapidly deteriorating relations with the West. Tass said "mutual interest in further continuation and deepening of Soviet-Iranian political contacts was reaffirmed" by the senior officials' talks.

Vorontsov's tour also appeared designed to assess the prospects of pursuing the recent resolution by the U.N. Security Council calling for an end to the Iran-Iraq war, diplomats said. Tass reported that during Vorontsov's talks "issues connected with the ongoing Iran-Iraq conflict were considered in detail in the light of" the U.N. resolution, which Moscow supported.

The Iranian news agency IRNA, monitored by western news services in London, said that Vorontsov had "condemned the governments involved" in the death of hundreds of Iranian pilgrims in Mecca last Friday. But Soviet Foreign Ministry spokesman Gennadi Gerasimov said at a press conference here today that he could not confirm the remarks.

Gerasimov said of the incidents at Mecca, "We regret any act of bloodshed."

Soviet-Iranian ties have long been strained. The fundamentalist Iranian leadership liquidated the pro-Soviet Tudeh party and supported Afghan guerrillas battling Soviet military forces. Tehran has also condemned the Soviet Union for supplying weapons to Iraq, a long-standing ally of Moscow.

However, contacts between Tehran and Moscow have recently increased. After Vorontsov last visited Tehran in June, Iranian Deputy Foreign Minister Javad Larijani traveled to Moscow last month. Western diplomats believe a trip to Tehran later this year by Soviet Foreign Minister Eduard Shevardnadze is under discussion.

Tass said the latest talks had produced agreement "for the implementation of large-scale projects of mutually beneficial economic cooperation," without specifying what these would be. The Iranian agency quoted Vorontsov as saying the Soviet government is willing to study projects in the field of energy, steel mills and industry.